Based on a play by W. A. McGuire and Guy Bolton with songs by Cole Porter, a West Point football star and a European princess fall in love.
Army halfback Dick Thorpe (Nelson Eddy) asks the coach to let Bill Delroy (Ray Bolger) play. Bill fumbles, but Dick scores the winning touchdown. Bill tells Dick that Mary is going to Europe. At a party a woman sings "Who Knows?" Dick dances with Rosalie (Eleanor Powell), who says he is conceited. Dick is ordered not to fly his plane. At Vasser Rosalie sings "I've Strange New Rhythm in My Heart" and tap dances. General Maroff tells Rosalie the King wants her home, but she assures Brenda (Ilona Massey) she won't marry Paul. Bill takes Dick to Rosalie's dormitory, and Dick sings "Rosalie." She invites him to her country.
Rosalie parades with Prince Paul (Tom Rutherford) and explains football. The King (Frank Morgan) sings "Why Should I Care?" He tells the Queen (Edna May Oliver) that Paul loves Brenda; but the Queen wants Rosalie to marry Paul. At the airport Bill says Dick is flying in from America. Mary Callahan (Virginia Grey) and her father expect a plane too. From his plane Dick calls the airport official Oloff (Billy Gilbert). At the festival Brenda sings "Spring Love Is in the Air." The King and Rosalie learn a plane is coming. Bill pretends that he was on the plane and is greeted by Mary. The King welcomes Dick, who disagrees with Bill. Dick tells the King he came for a girl. Dick sees Rosalie dance in an extravaganza. Dick finds Rosalie, asks her name, and says he loves her. Dick sings "In the Still of the Night." Chancellor (Reginald Owen) tells Rosalie the King has proclaimed her betrothal to Prince Paul, and Dick angrily runs off. Bill says that Mary found out he didn't fly and is going back to America. Bill lights fireworks, which set off a revolution. The King says in America people just sit down instead.
On a ship sea-sick Bill becomes friends with the King. Rosalie and Paul meet Bill. Rosalie tells Paul to join Brenda and asks where Dick is. General Maroff postpones Dick's court martial so he can escort Rosalie, who says she came to see him. The Chancellor and Queen plan to keep Rosalie from the ball. Dick shows Rosalie Flirtation Walk but is formal. Dick sees Paul kiss Brenda, who explains to Dick. Dick sings "To Love Or Not to Love." The Queen tells the King that Rosalie disappeared. Bill tells the King that Dick and Rosalie love each other. Dick is ordered to find Rosalie, who is disguised as a cadet by Bill. Rosalie gives marching commands and dances till her cap comes off. Rosalie runs into Dick, and she tells him to marry her. Bill says their mascot Mickey will be the King's ventriloquist dummy. Mickey tells the King to help Dick and Rosalie. The King tells the Queen and Chancellor that he abdicates so that Rosalie can marry Dick, who sings "Rosalie" at the wedding.
This musical comedy is absurdly romantic with Dick flying across the ocean for a date and Rosalie giving up her kingdom for a football player, but audiences that like singing, dancing, humor, and a love story won't mind that.